Semiconductor stripe laser

ABSTRACT

A semiconductor stripe laser has a first semiconductor region having a first conductivity type and a second semiconductor region having a different, second conductivity type. An active zone for generating laser radiation is located between the semiconductor regions. A stripe waveguide is formed in the second semiconductor region and is arranged to guide waves in a one-dimensional manner and is arranged for a current density of at least 0.5 kA/cm 2 . A second electrical contact is located on the second semiconductor region and on an electrical contact structure for external electrical contacting. An electrical passivation layer is provided in certain places on the stripe waveguide. A thermal insulation apparatus is located between the second electrical contact and the active zone and/or on the stripe waveguide.

This application claims priority to German Patent Application No. 102012 111 512.5 which was filed Nov. 28, 2012, and is incorporated hereinby reference.

TECHNICAL FIELD

A semiconductor stripe laser is provided.

SUMMARY OF THE INVENTION

Embodiments of the invention provide a semiconductor stripe laser whichhas a reduced voltage drop on an electrical contact surface.

In accordance with at least one embodiment, the semiconductor stripelaser emits laser radiation when used in the normal manner. Thesemiconductor stripe laser can be a pulsed laser or a continuous wavelaser.

In accordance with at least one embodiment, the semiconductor stripelaser is based upon a semiconductor material, preferably upon aIII-V-compound semiconductor material. The semiconductor material is,e.g., nitride-compound semiconductor material such asAl_(n)In_(1-n-m)Ga_(m)N or a phosphide-compound semiconductor materialsuch as Al_(n)In_(1-n-m)Ga_(m)P or even an arsenide-compoundsemiconductor material such as Al_(n)In_(1-n-m)Ga_(m)As, where 0≦n≦1,0≦m≦1 and n+m≦1 in each case. The semiconductor layer sequence canthereby have dopants and additional constituents. However, for the sakeof simplicity only the essential constituents of the crystal lattice ofthe semiconductor layer sequence, i.e., Al, As, Ga, In, N or P, arestated, even if they can be replaced and/or supplemented in part bysmall amounts of further substances.

In accordance with at least one embodiment, the semiconductor stripelaser has a first semiconductor region. The first semiconductor regionhas a first conductivity type. In particular, the first semiconductorregion is n-type. The first semiconductor region can have a singlesemiconductor layer or a plurality of semiconductor layers, for instancea cladding layer, a waveguide layer and/or electrical contact layers.

In accordance with at least one embodiment, the semiconductor stripelaser comprises a second semiconductor region. The second semiconductorregion has a second conductivity type which is different from the firstconductivity type. For example, the second semiconductor region isp-type. The second semiconductor region can also be formed from one or aplurality of semiconductor layers and can have a cladding layer, awaveguide layer and/or a contact layer.

In accordance with at least one embodiment, an active zone is located incertain places or on the entire surface between the first and secondsemiconductor regions. The active zone is arranged for generating thelaser radiation. The active zone has at least one pn-transition or atleast one quantum well structure.

In accordance with at least one embodiment, the first semiconductorregion, the active zone and the second semiconductor region directlyfollow one another along a growth direction of the semiconductormaterial. In a preferred manner, the semiconductor material isepitaxially deposited. In a preferred manner, the active zone and thesemiconductor regions then do not penetrate one another but ratheradjoin one another in particular in a planar and smooth manner.

In accordance with at least one embodiment, the semiconductor stripelaser has a stripe waveguide. In a preferred manner, the stripewaveguide is formed exclusively in the material of the secondsemiconductor region. The stripe waveguide is then free from the activezone. Alternatively, the stripe waveguide can comprise the active zoneand include materials of both semiconductor regions. For example, thestripe waveguide is formed by material being removed in the secondsemiconductor region, so that the stripe waveguide is a raised portionabove remaining regions of the semiconductor stripe laser.

In accordance with at least one embodiment, the stripe waveguide isarranged to guide waves of the laser radiation generated duringoperation, in particular to guide waves thereof in a one-dimensionalmanner. In other words, a refractive index progression is adjusted bythe stripe waveguide such that a laser mode is conducted in a specificregion. During normal use, the semiconductor stripe laser can be amonomode laser or even a multimode laser.

In accordance with at least one embodiment, during normal use a currentdensity in the stripe waveguide is at least 0.5 kA/cm² or at least 1.0kA/cm² or at least 1.5 kA/cm². The current density can be a currentdensity which is averaged over the entire stripe waveguide. In apreferred manner, a main current direction in the stripe waveguide isoriented perpendicularly to the active zone.

In accordance with at least one embodiment, the semiconductor stripelaser has a first electrical contact on the first semiconductor region.The first electrical contact can be provided over the entire surface of,or at certain points on, the first semiconductor region. For example,the first electrical contact is formed from a metal or a metal alloy. Itis possible for the semiconductor stripe laser to be attached to anexternal support via the first electrical contact, for instance bysoldering.

In accordance with at least one embodiment, a second electrical contactis located on the second semiconductor region. In particular, the secondelectrical contact is restricted to a boundary surface, facing away fromthe active zone, of the stripe waveguide. The second electrical contactis formed, e.g., from a metal, a metal alloy or a non-metallic,electrically conductive material.

In accordance with at least one embodiment, the second electricalcontact is located on an electrical contact structure. The electricalcontact structure is arranged for external electrical contacting of thesemiconductor component. For example, the electrical contact structurecomprises conductor tracks and electrical contact surfaces such assolder pads or bond pads.

In accordance with at least one embodiment, an electrical passivationlayer is provided in certain places on the stripe waveguide. Inparticular, the electrical passivation layer covers flanks of the stripewaveguide which can be partially or completely oriented in aperpendicular manner to the active zone. Preferably, during normal use,no current flows through the electrical passivation layer.

In accordance with at least one embodiment, a thermal insulationapparatus is located between the second electrical contact and theactive zone. The thermal insulation layer can be located partially orcompletely inside the stripe waveguide. Alternatively or in addition,the thermal insulation apparatus is attached externally to the stripewaveguide. The thermal insulation apparatus serves to reduce a dischargeof thermal energy out of the stripe waveguide and/or away from thesecond electrical contact. The thermal insulation apparatus serves toincrease a thermal resistance in the direction away from the stripewaveguide and/or from the second electrical contact. During normal useof the semiconductor stripe laser, the thermal insulation apparatuscauses a temperature on the second electrical contact to be increased incomparison with a semiconductor stripe laser without a thermalinsulation apparatus.

According to at least one embodiment, the semiconductor stripe laser hasa first semiconductor region with a first conductivity type and a secondsemiconductor region with a different, second conductivity type.Disposed between the first and the second semiconductor region is anactive zone for generating a laser radiation. A stripe waveguide isformed in the second semiconductor region and is arranged to guide wavesin a one dimensional manner and is arranged for a current density of atleast 0.5 kA/cm². A first electrical contact is provided on the firstsemiconductor region. A second electrical contact is located on thesecond semiconductor region and on an electrical contact structure forexternal electrical contacting of the semiconductor stripe laser. Anelectrical passivation layer is provided at certain places on the stripewaveguide. A thermal insulation apparatus is located between the secondelectrical contact and the active zone and/or on the stripe waveguide.

In particular, in the case of nitride-based semiconductor stripe lasers,there is a comparatively high voltage drop on an electrical contact.This voltage drop results in particular from Schottky barriers at ametal-semiconductor transition and from a comparatively small electricalconductivity of p-type gallium nitride through a low hole density byreason of the low-lying acceptor states of in particular magnesium inGaN. In the case of such low-lying acceptor states, only a comparativelysmall proportion of the acceptors are thermally activated. By increasingthe temperature on the electrical contact, it is possible to achieve ahigher proportion of thermally activated acceptors and it is herebypossible to reduce the voltage drop. Increased efficiency and increasedservice life can be associated with this.

In accordance with at least one embodiment, the thermal insulationapparatus comprises one or a plurality of semiconductor layers of thesecond semiconductor region or consists of at least one suchsemiconductor layer. At room temperature, an average thermalconductivity of this at least one semiconductor layer preferably amountsat the most to 60 W/mK or at the most to 40 W/mK. In particular, the atleast one semiconductor layer has a thermal conductivity which amountsat the most to 80% or 50% or 20% or 10% or 5% of the average thermalconductivity of the remaining layers of the second semiconductor region.

In accordance with at least one embodiment, the at least onesemiconductor layer of the thermal insulation apparatus is formed fromAl_(n)In_(m)Ga_(1-n-m)N. The parameter n amounts in this case preferablyto at least 0.05 or 0.1 or 0.2. Alternatively or in addition, n<0.9 or<0.8 or <0.6. Preferably, the parameter m is >0 and in particular is atleast 0.0001 or 0.001 or 0.01 and/or at the most 0.2 or 0.1. The value1-n-m amounts e.g. to at least 0.01 or 0.02 and/or at the most to 0.1 or0.05. The sum of n and m is ≦1 or preferably <1, in particular <0.9 orand/or >0.5 or >0.8 or >0.85.

In accordance with at least one embodiment, the thickness of the thermalinsulation apparatus is at least 1 nm or 10 nm or 20 nm and/or at themost 500 nm or 1000 nm or 2000 nm or at the most 10 μm. If theinsulation apparatus has a plurality of the semiconductor layers, thenan average layer thickness of these individual semiconductor layers ispreferably at least 0.1 nm or 0.5 nm or 1 nm and/or at the most 100 nmor 20 nm or 10 nm.

In accordance with at least one embodiment, a spacing between theinsulation apparatus and the second electrical contact is at least 100nm or 200 nm. Alternatively or in addition, this spacing is at the most1000 nm or 750 nm or 500 nm.

In accordance with at least one embodiment, a spacing between thethermal insulation apparatus and the active zone amounts at least to 200nm or 400 nm or 500 nm. Alternatively or in addition, this spacing is atthe most 1.5 μm or 1000 nm or 750 nm.

In accordance with at least one embodiment, the at least onesemiconductor layer of the thermal insulation apparatus completely spansthe stripe waveguide. In other words, the semiconductor layer is acontinuous layer which is present in the entire stripe waveguide and isoriented preferably in parallel with the active zone. The at least onesemiconductor layer is then present not only in a sub-region of thestripe waveguide.

In accordance with at least one embodiment, a layer of the secondsemiconductor region which is closest to the second electrical contactand can contact the second electrical contact is a layer consisting ofp-doped GaN. This layer can be free or substantially free of aluminumand indium. A dopant concentration of this layer is preferably at least10¹⁹/cm³ or 5×10¹⁹/cm³ and/or at the most 5×10²⁰/cm³ or 2×10²⁰/cm³. Adopant is in particular magnesium. In different regions of the secondsemiconductor region from this, a dopant concentration is, e.g., atleast 10¹⁸/cm³ or 5×10¹⁸/cm³ or 10¹⁹/cm³ and/or at the most 5×10¹⁹/cm³.Thermal conductivity can be reduced by means of such a comparativelyhigh dopant concentration.

In accordance with at least one embodiment, the plurality ofsemiconductor layers of the insulation apparatus form a multilayeredphonon barrier. In other words, the semiconductor layers are arranged tohave an increased resistance for lattice oscillations.

In accordance with at least one embodiment, the insulation apparatus hasa narrowed portion in the stripe waveguide or the insulation apparatusconsists of such a narrowed portion. The narrowed portion is locatedpreferably between the active zone and the second electrical contact.The narrowed portion is formed by the removal of material from thestripe waveguide.

In accordance with at least one embodiment, the narrowed portion extendspartially or completely along the stripe waveguide, along a mainpropagation direction of laser radiation in the stripe waveguide. Inparticular, within the scope of production tolerances the narrowedportion is formed symmetrically with respect to a plane perpendicular tothe active zone and in parallel with the main propagation direction.

In accordance with at least one embodiment, as seen in cross-section thestripe waveguide is formed in a trapezoidal manner, wherein a width ofthe stripe waveguide is reduced in the direction towards the activezone. Alternatively, it is possible that as seen in cross-section thestripe waveguide is formed in a T-shaped manner.

In accordance with at least one embodiment, the thermal insulationapparatus is produced at least partially by virtue of the fact that theelectrical contact structure on the stripe waveguide is structured toform a plurality of fingers. In combination, a total width of thefingers can be less than a width of the electrical contact structurewhich is not yet formed into fingers, as seen in plan view.

In accordance with at least one embodiment, the electrical contactstructure covers at the most 60% or 40% or 20% of the second electricalcontact, as seen in plan view. It is possible that the second electricalcontact is for the most part not covered by the electrical contactstructure.

In accordance with at least one embodiment, the thermal insulationapparatus comprises, or consists of, a thermal insulation layer. Thethermal insulation layer covers the electrical contact structure or thefingers of the electrical contact structure completely or partially.

In accordance with at least one embodiment, the thermal insulationapparatus comprises, or consists of, a further thermal insulation layer.The further thermal insulation layer is located directly on the secondsemiconductor region of the stripe waveguide and/or directly on thepassivation layer on the stripe waveguide.

In accordance with at least one embodiment, the further thermalinsulation layer is located in certain places between the electricalcontact structure and the second electrical contact. In this case,preferably one or a plurality of openings is/are formed in the furtherthermal insulation layer. In the at least one opening, the contactstructure is directly connected to the second contact.

In accordance with at least one embodiment, as seen in plan view theopenings make up a surface proportion of the stripe waveguide of at themost 55% or 35% or 25% or 15%. In other words, a total area of theopenings can be comparatively small relative to the total area of thestripe waveguide.

In accordance with at least one embodiment, the thermal insulation layerand/or the further thermal insulation layer is/are formed by means of alayer stack having a plurality of layers. A material of the insulatinglayers is preferably different from a material of the stripe waveguide,the passivation layer, the second electrical contact and/or theelectrical contact structure. For example, the layers of the layer stackare each formed from an oxide or nitride. For example, the layer stackhas layers consisting of two different materials which follow oneanother alternately. The layer stack preferably comprises at least fouror eight or twelve layers and/or at the most 100 or 50 or 25 layers.

In accordance with at least one embodiment, the insulation apparatus isproduced partly or completely by virtue of the fact that the electricalcontact structure is formed partly or completely by means of a layerstack. The layer stack comprises, e.g., at least three or five or eightlayers and/or at the most 25 or 20 or 15 layers. It is possible that atleast one layer of the layer stack is formed from an electricallyconductive oxide or nitride. If the layer stack alternately has metalliclayers and layers consisting of an electrically conductive oxide ornitride, then a thickness of the metallic layers is preferably less thana thickness of the layers of the oxide or nitride.

In accordance with at least one embodiment, the thermal insulationapparatus is produced partly or completely by virtue of the fact thatthe second electrical contact comprises one or a plurality of layerswhich are formed from an electrically conductive oxide or nitride. It ispossible that the second electrical contact consists of at least onesuch layer.

In accordance with at least one embodiment, the thermal insulationapparatus is produced partly or completely by virtue of the fact thatthe thermal conductivity of a material is reduced in at least onesub-area of the second semiconductor region in the stripe waveguide bymeans of ion implantation and/or partial destruction of a crystalstructure, e.g., to at the most 50% or 30% of a value of the thermalconductivity prior to the corresponding treatment. The sub-area islocated preferably completely within the stripe waveguide and betweenthe second electrical contact and the active zone. It is possible thatthis sub-area is restricted to a material of the second semiconductorregion. In the sub-area, an electrical conductivity can also be reducedor can be negligible.

In accordance with at least one embodiment, this sub-area is spacedapart from the second contact and has a smaller width than the stripewaveguide. In particular, two sub-areas are present which extend inparallel with the main propagation direction on flanks of the stripewaveguide. As seen in cross-section, the sub-area can be formed in asimilar manner to a half cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

A semiconductor stripe laser described in this case will be explained inmore detail hereinafter with reference to the drawing and with the aidof exemplified embodiments. Like elements are indicated by likereference numerals in the individual figures. The elements illustratedin the figures and their size relationships among one another should notbe regarded as true to scale. Rather, individual elements may berepresented with an exaggerated size for the sake of betterrepresentability and/or for the sake of better understanding.

FIGS. 1 to 15 and 19 show schematic sectional views or schematicsectional views together with schematic plan views of exemplifiedembodiments of semiconductor stripe lasers described in this case; and

FIGS. 16 to 18 show schematic sectional views of arrangements comprisingsemiconductor stripe lasers described in this case.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 illustrates an exemplified embodiment of a semiconductor stripelaser 1. The semiconductor stripe laser 1 has a first semiconductorregion 11 and a second semiconductor region 13. Located between thesemiconductor regions 11, 13 is an active zone 12 for generating laserradiation. A stripe waveguide 3 is formed in the second semiconductorregion 13 which in particular is of a p-type. As seen in cross-section,the stripe waveguide 3 is configured in a rectangular manner, anapproximately rectangular manner or, in contrast to the illustration, ina trapezoidal manner. The stripe waveguide 3 extends along a z-directionperpendicular to the plane of the drawing, see also FIG. 7B.

An electrical passivation layer 5 is provided on flanks of the stripewaveguide 3. The passivation layer 5 can also extend on boundarysurfaces of the second semiconductor region 13 which are oriented inparallel with the active zone 12.

Located on a side of the first semiconductor region 11 facing away fromthe active zone 12 is a first electrical contact 41 which, unlike theillustration, can also be provided only in certain regions on the firstsemiconductor region 11. Located on a side of the stripe waveguide 3facing away from the active zone 12 is a second electrical contact 43which is arranged to impress current into the second semiconductorregion 13. The second electrical contact 43 is formed preferably by ametal or a metal alloy. The second electrical contact 43 can be formedby a plurality of metallic layers.

Located on a side, facing away from the active zone 12, of thepassivation layer 5 or of the optional insulation layer 25 is anelectrical contact structure 44, only part of which is illustrated inFIG. 1. The semiconductor stripe laser 1 can be electrically externallycontacted via the contact structure 44.

Furthermore, the semiconductor stripe laser 1 comprises a thermalinsulation apparatus 2. The thermal insulation apparatus 2 is formed bymeans of a semiconductor layer 23 in the second semiconductor region 13.The semiconductor layer 23 is oriented in parallel with the active zone12 and is spaced apart from the active zone 12 and the second electricalcontact 43. The semiconductor layer 23 is formed from AlInGaN with aindium proportion of preferably at least 0.1% or 2% and/or at the most20% or 3% and with an aluminum proportion of preferably at least 5% or10% or 20%. This type of semiconductor layer 3 serves to reduce thermalconductivity, specifically in comparison with GaN, to a considerableextent, e.g., by at least a factor of 2 or by at least a factor of 5 orby at least a factor of 10, see also document Liu, et al., Journal ofApplied Physics, vol. 97, page 073710 from 2005. The disclosure contentof this document is incorporated by reference.

The semiconductor stripe laser 1 is arranged for operation withrelatively high current densities. As a result, heat is produced bymeans of an electrical resistance in particular on a boundary surfacebetween the second electrical contact 43 and the second semiconductorregion 13. By means of the thermal insulation apparatus 2, this heat isprevented from being discharged, so that a temperature of the secondsemiconductor region 13 is increased on the electrical second contact43. As a result, a hole density on the second electrical contact 43 canlikewise be increased by reason of the higher temperature, so that avoltage drop on the second electrical contact 43 can be reduced.

Since the insulation apparatus 2 is located between the active zone 12and the second electrical contact 43, efficient cooling of the activezone 12 is possible at the same time in particular over the firstelectrical contact 41.

Optionally, as also in all of the other exemplified embodiments, thepassivation layer can have a thermal insulation layer 25 providedthereon which is to be assigned to the insulation apparatus 2. Thethermal insulation layer 25 is formed preferably from an electricallyconductive oxide or nitride and is configured in particular not in amonocrystalline manner but rather in a polycrystalline or amorphousmanner. For example, the insulation layer 25 comprises, or consists of,one or a plurality of the materials stated hereinafter: indium-tinoxide, zinc oxide, fluorine-tin oxide, aluminum-zinc-oxide,antimony-zinc-oxide, titanium nitride, titanium-tungsten-nitride,titanium-oxynitride, an organic semiconductor material, an electricallyconductive polymer and an electrically conductive resin, a syntheticresin having an electrically conductive, for instance metallic adjunct,a non-monocrystalline, inorganic semiconductor material, a poorlythermally conductive metal, such as nickel, titanium, platinum, bismuth,indium or antimony.

FIG. 2 illustrates a further exemplified embodiment of the semiconductorstripe laser 1. The thermal insulation apparatus 2 is formed from alayer stack of a plurality of the semiconductor layers 23 a-23 e. Thelayers 23 a-23 e preferably follow one another directly and are eachbased upon InAlGaN.

In the case of the exemplified embodiment as shown in FIG. 3, theinsulation apparatus 2 is formed in the stripe waveguide 3 by virtue ofthe fact that a material composition or a material structure is changedin sub-areas 26 by means of implantation of ions, by the introduction ofmaterial by means of diffusion or for instance by means of electronradiation. As a result, thermal conductivity is reduced in sub-areas 26which extend along the z-direction longitudinally of the stripewaveguide 3. A region between the sub-areas 26, along the y-direction,has, e.g., a width of at least 20% or 25% and/or of at the most 40% or50% of a total width of the stripe waveguide 3.

In the case of the exemplified embodiment as shown in FIG. 4, the sideof the passivation layer 5 facing away from the active zone 12 has thethermal insulation layer 25 provided thereon which serves to produce theinsulation apparatus 2. Unlike the illustration, the insulation layer 25preferably has a relatively large thickness, e.g., at least 200 nm or500 nm or 1 μm. The materials stated in conjunction with FIG. 1 can beused as the materials.

As in all of the other exemplified embodiments, a height H of the stripewaveguide 3 is preferably at least 400 nm or 600 nm. Alternatively or inaddition, the height H is, e.g., at the most 5 μm or 3 μm or 1.5 μm. Awidth B of the stripe waveguide 3 amounts, e.g., to at least 1 μm or 1.5μm and alternatively or in addition preferably at the most to 100 μm or50 μm or 15 μm. An angle β between the main surfaces of the passivationlayer 5 at the base of the stripe waveguide 3 is, e.g., approximately270°, for instance with a tolerance of at the most 20° or 10°.

In the case of the exemplified embodiment as shown in FIG. 5, a narrowedportion 21 is formed at the base of the stripe waveguide 3 and forms theinsulation apparatus 2. An angle between the active zone 12 and theflanks of the stripe waveguide 3 exceeds 270° or 285°. The angle βamounts preferably at the most to 320° or 305°.

In the region of the narrowed portion 21, the thermal insulation layer25 can have a greater thickness. However, in contrast to theillustration, it is also possible that a thickness of the insulationlayer 25 is not enlarged in the region of the narrowed portion.

As shown in FIG. 6, the stripe waveguide 3 is configured in a T-shapedor I-shaped manner, in order to produce the insulation apparatus 2. Inthe region of the narrowed portion 21, lateral surfaces of the stripewaveguide 3 are oriented perpendicular or approximately perpendicular tothe active zone 12. Alternatively, the lateral surfaces can have anangle of up to 40° to a perpendicular of the active zone 12. As in allof the other exemplified embodiments, a cross-section of the stripewaveguide 3 can remain the same or approximately the same along thez-direction.

A region directly on the second electrical contact 43 preferably has athickness A of at the most 2 μm or 500 nm or 100 nm and/or of at least 5nm or 10 nm or 20 nm. The narrowed portion 21 preferably has a thicknessB of at least 1 nm or 10 nm or 100 nm and/or of at the most 2 μm or 500nm. A width C of the narrowed portion 21 is e.g. at least 20 nm or 100nm or 250 nm. The width C preferably amounts at the most to 90% or 80%or 70% or 60% of the total width of the stripe waveguide 3. A height Eof the base of the stripe waveguide 3 is greater than or equal to 0 andis, e.g., at least 100 nm or 200 nm and/or at the most 500 nm or 200 nm.It is possible that a thickness of the second semiconductor region 13,in the y-direction next to the stripe waveguide 3, is at least 20 nm or40 nm or 100 nm and/or at the most 600 nm or 400 nm or 300 nm. A lengthL of the stripe waveguide is preferably at least 300 nm or 600 nm and/orat the most 5 mm or 2 mm, see also FIG. 7B.

As shown in FIG. 7, the electrical contact structure has a bond pad 44 band a conductor track 44 a. On the stripe waveguide 3, the conductortrack 44 a is structured to form a plurality of narrow fingers 44 c. Theindividual fingers 44 c have, e.g., a width of at least 0.5 μm and/or ofat the most 20 μm. A spacing between adjacent fingers 44 c is preferablyat least 0.5 μm or 5 μm and/or at the most 52 μm. By virtue of the factthe fingers 44 c are narrow, heat dissipation is reduced by the metalliccontact structure and as a result the insulation apparatus 2 isproduced. It is possible that the fingers 44 c are restricted to theside of the stripe waveguide 3 facing away from the active zone 12, andto only one of the flanks of the stripe waveguide 3. In contrastthereto, the fingers 44 c can also be provided on both flanks of thestripe waveguide 3, cf. FIG. 8.

In the case of the exemplified embodiment as shown in FIG. 8, thefingers 44 c are covered by a further thermal insulation layer 24.Located between the fingers 44 c and the second electrical contact 43 isthe thermal insulation layer 25. The further thermal insulation layer 24can be an electrically insulating or even an electrically conductivelayer.

A main emission direction of the semiconductor stripe laser 1 lies inthe y-z-plane and extends preferably in parallel with the z-direction. Amain current direction for supplying current to the active zone 12extends along the x-direction, as also in all of the other exemplifiedembodiments.

As shown in FIGS. 9 and 10, the contact structure 44 a, 44 b is notstructured into fingers in regions but rather over the entire surface.Located between the contact structure 44 a and the second contact 43 isthe passivation layer 5. Formed in the passivation layer 5, are aplurality of openings 29, in which the contact structure 44 a is indirect contact with the second contact 43.

The second electrical contact 43 preferably covers the entire side ofthe stripe waveguide 3, facing away from the active zone 12, or at leasta large part of this side, e.g., at least 85% or 70%. Unlike theillustration, it is possible that the second contact 43 has a smallerwidth than the stripe waveguide 3, as is also possible in all of theother exemplified embodiments.

Unlike the illustration shown in FIG. 9B, it is not necessary that theopenings 29 extend along the y-direction. The openings can also berestricted to regions, e.g., along the x-direction. The openings 29preferably make up an area proportion of at the most 50% or 30%, inrelation to an area of the second electrical contact 43 and as seen planview. Likewise, the openings 29 can be produced as a dot pattern or as across pattern, see also FIG. 10B.

In the case of the exemplified embodiment as shown in FIG. 11, thethermal insulation apparatus 2 is produced exclusively by virtue of thefact that the contact structure is formed into the narrow fingers 44 cin the region of the stripe waveguide 3.

The schematic view of FIG. 12 shows that the passivation layer 5 whichat the same time forms the insulation apparatus 2 is a multilayeredstructure having the layers 25 a-25 g. A thickness of the passivationlayer 5 then preferably amounts to at least 200 nm or 500 nm or 1 μm. Athickness of the individual layers is preferably at least 0.1 nm or 1 nmand/or at the most 10 nm or 20 nm or 100 nm. The multilayered structurepreferably has as many boundary surfaces as possible and is formed,e.g., by means of alternating layers of silicon dioxide and siliconnitride, of aluminum oxide and silicon oxide, of aluminum oxide andzirconium oxide, of silicon oxide and zirconium oxide, of siliconnitride and zirconium oxide, of titanium oxide and silicon oxide or ofhafnium oxide and zirconium oxide. Furthermore, the layer stack can havea combination of layers consisting of oxides or nitrides or oxynitridesof Al, Ce, Ga, Hf, In, Mg, Nb, Rh, Sb, Si, Zn, Ta, Ti, Sn or Zr.

As shown in FIG. 13, the conductor tracks 44 a of the contact apparatusare formed as layer stacks, so that thermal conductivity of theconductor track 44 a is reduced and the thermal insulation apparatus 2is thus formed. A total thickness of the conductor track 44 a is, e.g.,at least 0.1 nm or 50 nm or 100 nm and/or at the most 1 μm or 5 μm or 20μm. The individual layers of the layer stack preferably each have athickness of at least 0.1 nm or 1 nm and/or at the most 20 nm or 100 nmor 500 nm. Preferably, the conductor track 44 a is restricted to a flankof the stripe waveguide 3.

For example, the layer stack is formed by a combination of differentmetals, such as titanium and platinum, or by a combination of layers ofa metal and electrically conductive non-metals or organic or inorganicsemiconductors, e.g., consisting of titanium and indium-tin-oxide, byaluminum and titanium-tungsten-nitride, by zinc oxide and titanium andgold and titanium and zinc oxide. The layers of said materials canfollow one another in alternating fashion.

As shown in FIG. 14, a comparatively poorly thermally conductive,electrically conductive layer or layer stack is provided between thecontact apparatus 44 and the second electrical contact 43. The layerstack can be formed from the materials, as explained in conjunction withFIG. 13. A bond pad metallization, for instance consisting of titaniumand gold, of titanium, platinum and gold or of chromium, platinum andgold can be provided on this layer stack 25.

In the case of the exemplified embodiment as shown in FIG. 15, thesecond electrical contact 43 is formed by means of a metal layer havinga low thermal conductivity, e.g., consisting of platinum, palladium,nickel or rhodium. It is likewise possible that the second electricalcontact 43 is formed by means of a layer of an electrically conductiveoxide or nitride, such as indium-tin-oxide or zinc oxide. The secondelectrical contact 43 can also be formed by means of a layer stack.Unlike the illustration in FIG. 15, electricity can also be supplied ina similar manner to the exemplified embodiments as shown in FIG. 9 to11, 13 or 14.

In a particularly preferred manner, several of the exemplifiedembodiments are combined together where technically feasible. Inparticular, the exemplified embodiments as shown in FIGS. 1 and 15 or asshown in FIGS. 1 and 9 or as shown in FIGS. 11 and 13 or as shown inFIGS. 1, 11 and 15 or as shown in FIGS. 9 and 15 are combined together.

FIGS. 16 to 18 show arrangements of a semiconductor stripe laser 1,which is described in this case, on a support 7. The support 7 is, forinstance, a printed circuit board and/or a heat sink.

The stripe waveguide 3 faces away from the support 7 as shown in FIG. 16and faces towards the support 7 as shown in FIGS. 17 and 18. In the caseof the arrangement as shown in FIG. 16, which is preferred, atemperature on the second electrical contact 43 during operation isgreater than in the active zone, not illustrated, based upon a normaluse of the semiconductor laser 1. FIG. 16 also illustrates a bond wire6.

As shown in FIG. 18, the electrical contact structure 44 x, 44 y isdivided into two. In a first part 44 x between the support 7 and the webwaveguide 3 and on flanks of the web waveguide 3 close to the support 7,the contact structure 44 x has a solder with a multiplicity of cavities.As a result, thermal conductivity of the contact structure 44 x can bereduced. For example, the contact structure 44 x has a thermalconductivity of at the most 50% or 25% of the thermal conductivity ofthe contact structure 44 y which is soldered homogeneously and issubstantially free of cavities. Such cavities are also referred to asbubbles or blowholes.

The cavities in the contact structure 44 x preferably have a size of atleast 0.1 μm and/or at the most 50% or 90% of a width of the stripewaveguide 3. At least 25% or 40% and/or at the most 75% or 50% of thecontact structure 44 x extends along the flanks. Furthermore, cooling ofthe web waveguide 3 in a lateral direction is possible via the contactstructure 44 y. The contact structure 44 y is, e.g., at least 3-times or5-times the width of the web waveguide 3.

In the case of the exemplified embodiment of the semiconductor stripelaser 1 as shown in FIG. 19, the insulation apparatus 2 is formed bymeans of a gap. The gap is evacuated or filled with gas, for instancewith air. The gap can be located directly on the passivation 5 or canextend spaced apart from the passivation 5. A thickness of the gapamounts preferably at least to 1 nm or 10 nm and/or at the most to 200nm or 100 nm. An angle of the gap, relative to the x-direction, is inparticular between 0° and 15° inclusive or between 3° and 10° inclusive.The gap extends to at least 1% or 20% or 50% and/or to at the most 99%or 90% of a thickness of the contact structure 44, along thex-direction.

As is also the case in all of the other exemplified embodiments, thethickness of the contact structure 44 can exceed the height of the webwaveguide 3, in the x-direction. In contrast thereto, the thickness ofthe contact structure 44 can be less than the height of the webwaveguide 3. In the exemplified embodiments, it is likewise possible ineach case that the passivation layer 5 extends onto a side of the secondcontact 43 facing away from the active zone 12. In the case of oneembodiment of the contact structure 44 for instance as shown in FIG. 9,it is also possible that the gap on different sides of the stripewaveguide 3 is also formed differently and not symmetrically.

The invention described in this case is not limited by the descriptionusing the exemplified embodiments. Rather, the invention includes anynew feature and any combination of features included in particular inany combination of features in the claims, even if this feature or thiscombination of features itself is not explicitly stated in the claims orexemplified embodiments.

What is claimed is:
 1. A semiconductor stripe laser comprising: a firstsemiconductor region of a first conductivity type; a secondsemiconductor region of a second conductivity type that is differentthan the first conductivity type; an active zone configured to generatelaser radiation, the active zone located between the first and thesecond semiconductor region; a stripe waveguide formed in the secondsemiconductor region, arranged to guide waves in a one-dimensionalmanner, and arranged for a current density of at least 0.5 kA/cm²; afirst electrical contact on the first semiconductor region; a secondelectrical contact on the second semiconductor region and on anelectrical contact structure for external electrical contacting of thesemiconductor stripe laser; an electrical passivation layer provided incertain places on the stripe waveguide; and a thermal insulationapparatus located between the second electrical contact and the activezone, the thermal insulation apparatus being located completely orpartially inside the stripe waveguide; wherein the thermal insulationapparatus is formed by one or a plurality of semiconductor layers of thesecond semiconductor region and an average thermal conductivity of theone or a plurality of semiconductor layers amounts at the most to 60W/mK at room temperature; wherein the one or plurality of semiconductorlayers of the insulation apparatus comprises Al_(n)In_(1-n-m)Ga_(m)N,where 0.5<n<0.9 and 0.01≦1-n-m≦0.05 and n+m<1; wherein a thickness ofthe thermal insulation apparatus is at least 20 nm, a spacing betweenthe thermal insulation apparatus and the second electrical contact is atleast 100 nm and a spacing between the thermal insulation apparatus andthe active zone is at least 200 nm; wherein a layer of the secondsemiconductor region located closest to the second electrical contact isformed from p-doped GaN; and wherein the one or plurality ofsemiconductor layers completely spans the stripe waveguide.
 2. Thesemiconductor stripe laser according to claim 1, wherein the thermalinsulation apparatus comprises a plurality of semiconductor layers,wherein the semiconductor layers form a multilayered phonon barrier. 3.The semiconductor stripe laser according to claim 1, wherein the thermalinsulation apparatus comprises a further thermal insulation layerlocated directly on the second semiconductor region of the stripewaveguide or directly on the passivation layer of the stripe waveguide.4. The semiconductor stripe laser according to claim 3, wherein thefurther thermal insulation layer is located in certain places betweenthe electrical contact structure and the second electrical contact; andwherein openings are formed in the further thermal insulation layer, theelectrical contact structure being connected to the second electricalcontact in the openings and wherein, as seen in plan view, the openingscover a total of at the most 25% of the stripe waveguide.
 5. Thesemiconductor stripe laser according to claim 3, wherein the thermalinsulation layer or the further thermal insulation layer are formed by alayer stack; and wherein layers of the layer stack are each formed froman oxide or nitride.
 6. The semiconductor stripe laser according toclaim 1, wherein the thermal insulation apparatus is produced at leastpartly by virtue of the fact that the thermal conductivity of a materialof the second semiconductor region is reduced in a sub-area by ionimplantation or partial destruction of a crystal structure; and whereinthis sub-area is spaced apart from the second electrical contact and hasa smaller width than the stripe waveguide.
 7. A semiconductor stripelaser comprising: a first semiconductor region of a first conductivitytype; a second semiconductor region of a second conductivity type thatis different than the first conductivity type; an active zone configuredto generate laser radiation, the active zone located between the firstand the second semiconductor region; a stripe waveguide formed in thesecond semiconductor region, arranged to guide waves in aone-dimensional manner, and arranged for a current density of at least0.5 kA/cm²; a first electrical contact on the first semiconductorregion; a second electrical contact on the second semiconductor regionand on an electrical contact structure for external electricalcontacting of the semiconductor stripe laser; an electrical passivationlayer provided in certain places on the stripe waveguide; and a thermalinsulation apparatus located at least between the second electricalcontact and the active zone, the thermal insulation apparatus beinglocated completely or partially inside the stripe waveguide; wherein thethermal insulation apparatus is formed by a plurality of semiconductorlayers of the second semiconductor region and an average thermalconductivity of the plurality of semiconductor layers amounts at themost of 60 W/mK at room temperature; and wherein the plurality ofsemiconductor layers form a multilayered phonon barrier.
 8. Asemiconductor stripe laser comprising: a first semiconductor region of afirst conductivity type; a second semiconductor region of a secondconductivity type that is different than the first conductivity type; anactive zone configured to generate laser radiation, the active zonelocated between the first and the second semiconductor region; a stripewaveguide formed in the second semiconductor region, arranged to guidewaves in a one-dimensional manner, and arranged for a current density ofat least 0.5 kA/cm²; a first electrical contact on the firstsemiconductor region; a second electrical contact on the secondsemiconductor region and on an electrical contact structure for externalelectrical contacting of the semiconductor stripe laser; an electricalpassivation layer provided in certain places on the stripe waveguide;and a thermal insulation apparatus located on the stripe waveguide;wherein the thermal insulation apparatus is produced at least partiallyby virtue of the fact that the electrical contact structure on thestripe waveguide is formed into a plurality of fingers and covers at themost 40 percent of the second electrical contact, as seen in a plan viewof the stripe waveguide.
 9. The semiconductor stripe laser according toclaim 8, wherein the thermal insulation apparatus comprises a thermalinsulation layer that at least partially covers the electrical contactstructure on the stripe waveguide.
 10. A semiconductor stripe lasercomprising: a first semiconductor region of a first conductivity type; asecond semiconductor region of a second conductivity type that isdifferent than the first conductivity type; an active zone configured togenerate laser radiation, the active zone located between the first andthe second semiconductor region; a stripe waveguide formed in the secondsemiconductor region, arranged to guide waves in a one-dimensionalmanner, and arranged for a current density of at least 0.5 kA/cm²; afirst electrical contact on the first semiconductor region; a secondelectrical contact on the second semiconductor region and on anelectrical contact structure for external electrical contacting of thesemiconductor stripe laser; an electrical passivation layer provided incertain places on the stripe waveguide; and a thermal insulationapparatus located between the second electrical contact and the activezone; wherein the thermal insulation apparatus comprises a furtherthermal insulation layer located directly on the second semiconductorregion of the stripe waveguide or directly on the passivation layer ofthe stripe waveguide, wherein the further thermal insulation layer islocated in certain places between the electrical contact structure andthe second electrical contact; and wherein openings are formed in thefurther thermal insulation layer, the electrical contact structure beingconnected to the second electrical contact in the openings and wherein,as seen in plan view, the openings cover a total of at the most 25percent of the stripe waveguide.
 11. A semiconductor stripe lasercomprising: a first semiconductor region of a first conductivity type; asecond semiconductor region of a second conductivity type that isdifferent than the first conductivity type; an active zone configured togenerate laser radiation, the active zone located between the first andthe second semiconductor region; a stripe waveguide formed in the secondsemiconductor region, arranged to guide waves in a one-dimensionalmanner, and arranged for a current density of at least 0.5 kA/cm²; afirst electrical contact on the first semiconductor region; a secondelectrical contact on the second semiconductor region and on anelectrical contact structure for external electrical contacting of thesemiconductor stripe laser; an electrical passivation layer provided incertain places on the stripe waveguide; and a thermal insulationapparatus located between the second electrical contact and the activezone; wherein the thermal insulation apparatus comprises a furtherthermal insulation layer located directly on the second semiconductorregion of the stripe waveguide or directly on the passivation layer ofthe stripe waveguide; wherein at least one of the thermal insulationlayer and the further thermal insulation layer are formed by a layerstack; and wherein layers of the layer stack are each formed from andoxide or nitride.
 12. A semiconductor stripe laser comprising: a firstsemiconductor region of a first conductivity type; a secondsemiconductor region of a second conductivity type that is differentthan the first conductivity type; an active zone configured to generatelaser radiation, the active zone located between the first and thesecond semiconductor region; a stripe waveguide formed in the secondsemiconductor region, arranged to guide waves in a one-dimensionalmanner, and arranged for a current density of at least 0.5 kA/cm²; afirst electrical contact on the first semiconductor region; a secondelectrical contact on the second semiconductor region and on anelectrical contact structure for external electrical contacting of thesemiconductor stripe laser; an electrical passivation layer provided incertain places on the stripe waveguide; and a thermal insulationapparatus located on the stripe waveguide; wherein the thermalinsulation apparatus is produced at least partly by virtue of the factthat the electrical contact structure is formed partially or completelyby a layer stack that comprises at least one layer of an electricallyconductive oxide.